This article on Napoleonic Artillery was originally drafted over 20 years ago as part of a book which I never finished. There is much better research on Napoleonic Artillery available now, such as books by Kevin Kiley, Anthony Dawson, Paul Dawson and Stephen Summerfield. However, having published articles on my similar old research into Infantry and Cavalry, I thought that I would add this one for completeness.
During the 18th century all major nations had idiosyncratic command arrangements for artillery which complicated the integration of artillery into the overall army structure. The roots of this lay within the way in which armies were originally raised in earlier centuries. Most countries did not have standing armies, but relied on raising one when required. The monarch would turn to his noblemen, or other gentlemen of means, and ask them to raise units of infantry and cavalry, in return for which they would be paid sums of money. Frequently the entire equipping of such units was left to the discretion of the officers who raised them. Artillery was different because it was far more costly and also far more powerful. It was the normal practice for there to be a central stock of artillery held in one or more fortresses and owned entirely by the monarch. All major nations therefore created a separate command structure for this artillery element. In Britain the Board of Ordnance operated as a separate government department and the Master-General of the Ordnance held a seat in the British cabinet. In France similar authority was wielded by the Grand Master of Artillery and Austria likewise had a separate and autonomous artillery command structure. 
By the outbreak of the Napoleonic wars some nations, notably France and Prussia, had assimilated their artillery into the normal army command structure. Britain however retained her original separate chains of command, sometimes to the frustration of commanders in the field.
During the 18th century artillery officers of some nations were treated as inferior “technicians”. This was particularly so in Prussia where the view was:
“Live with Prussian officers and you will see the officers of the infantry, cavalry and hussars assume a great superiority over those of the artillery. The latter seem to realise their lowly status, in a manner of speaking. The other officers intermingle and seek each other out regardless of regiment or arm, but it is altogether exceptional for any friendship to be formed between the gunner officers and the officers of the rest of the army.” 
This view had been somewhat modified by the outbreak of the Revolutionary wars and was never so extreme as this in Britain and France. Many British memoirs of the Napoleonic wars testify to close friendships and mutual professional respect between artillery officers and those of the cavalry and infantry. The lack of prejudice was such that a well connected officer such as John Aitchison could prefer to enter the Royal Artillery  and it was only to please his father that he entered the 3rd (Scots) Guards.
In egalitarian France the fact that Napoleon himself was an artillery officer did much to dispel any lingering prejudices, and it is interesting that the memoirs of the aristocratic Cuirassier officer de Gonneville showed a close friendship with an artillery officer.
“The battery of artillery with us was commanded by a captain of the name of Hurlaux, a man of the noblest and best disposition I ever met. I became very intimate with him; and, though this friendship was broken by our various movements and mutual silence, it was renewed in 1835, and lasted till his death in 1849.” 
Artillery organisation in all armies was further compounded by the fact that the various components required to operate in the field were organised in at least two if not three entirely separate groups. The men were organised as artillery companies that did not own their guns nor in most nations did they own the transport to move them. Such companies comprised a number of trained artillery officers and men, who in theory could man guns of any calibre, in the field or in fortifications. Such companies were often grouped together in regiments for administrative purposes but such regiments had no tactical role.
The second element was the guns themselves, which were held separately in artillery parks. The teams of horses and drivers to move the guns formed a third group known as the artillery train. In a few nations, notably Prussia and Russia, artillery train personnel were integrated into artillery companies. When it was necessary for artillery to accompany an army a number of companies of artillery would be detailed for this duty, possibly from entirely different artillery regiments. A number of guns would then be assigned to them from the park, together with a number of drivers and teams from the artillery train to move the guns. This marrying together of three separate elements is the origin of the use of the term “brigade” to describe a British artillery battery.
Early 18th century field artillery was of small calibre and relatively immobile. It was also essentially a direct fire weapon, and overhead fire was very rare. Up to the mid 18th century it was therefore normal for artillery to be parcelled out as a series of 2 gun detachments across the front of the battle line, filling the gaps between battalions. The number of guns which an artillery company could crew was therefore of no particular consequence and as a result there were widely varying sizes of artillery companies in different nations and even within the artillery of any one nation.
Once the artillery company and its guns were married together and moved to a firing position by the train, this gun position itself was known as a battery. The term “battery” gradually changed its usage during the Napoleonic wars until it became synonymous with the artillery company itself. The British at Culloden in 1745 had a single company which manned 16 artillery pieces (10 guns and 6 mortars) whilst the two companies at Minden in 1759 manned 9 guns each.  Most Prussian 18th century artillery companies manned batteries of 10 guns but at Rossbach in 1757 the Prussians used an 18 gun battery.
One particular feature of 18th century artillery organisation was the use of detachments of “battalion guns”. These normally comprised two small calibre pieces crewed by specialists who were on the strength of an infantry regiment or battalion. Their role was to provide direct fire support to the infantry unit.
Advances in technology during the century led to greater calibres (more range) and better carriage design leading to greater mobility. Even although the higher calibre guns were more mobile than their predecessors, they required proportionately more crew per gun. This particularly arose because of the need to manhandle the gun back into position after it had recoiled from each firing, and there was a direct correlation between gun calibre and the number of men required to do this. As the 18th century progressed the size of artillery companies standardised to approximately 100 men and the number of guns served by such a company fell to 6 – 8.
As a result of the increase in calibre of guns many nations adopted the practice of supplementing their gun crews with additional personnel. The artillery company would provide the core of trained men but untrained labour would be provided to assist in manhandling the heavy guns. The Austrian army formed a separate Artillerie-Handlanger-Corps to assist in this role whilst the French army relied on detachments from the infantry formation who they were supporting. The British army was one of the few which did not rely on this practice, and as a consequence British had a higher ratio of trained artillerymen per gun other nations. The numbers of men required to crew guns of various calibres is at table 1.
Because the French and Austrians used non-specialist personnel to help to crew their guns they could have relatively large numbers of small artillery companies. The British specified the same number of crew for all calibres, 9 men to fire the gun and a further 6 required to manhandle it. The British system assumed that these were all trained gunners, which meant that their artillery companies tended to be larger than those of other nations despite having less guns per company. The British artillery handbook does however have a table showing how guns of any calibre can be crewed by any number of men, down to a minimum of three. 
The effect of greater mobility was that artillery could be increasingly repositioned on the battlefield and this created the need for a better artillery train system. Originally artillery was moved by teams of civilian contractors, who would site the artillery in a fixed point on the battlefield and then retire. By the end of the 18th century this was no longer adequate and all armies raised units of military drivers for their trains, the Austrians doing so in 1776, the British in 1794 and the French in 1800. The vestiges of the old system remained however in that, for the most part, these train personnel were in separate units to the artillery companies themselves and were accorded a more lowly status within the military hierarchy.
By the commencement of the Revolutionary Wars most nations formed their artillery into 6 or 8 gun companies, which eventually became known as batteries (a terminology previously reserved for the gun position itself). The optimum size of a battery was dictated by the number of guns which one commander could control. Since these were deployed spaced out at a frontage of 10 to 20 yards per gun this led most nations to use to batteries of some 6 to 8 guns, except the Russians using 12.
Artillery had seen significant technical improvements since the 18th century. Gun carriages and limber design had been improved and this not only increased the mobility of artillery but also permitted larger calibre guns to be used as Field Artillery. The greater mobility and firepower of Napoleonic Artillery led to it being more usually used as complete batteries which changed position several times during a battle so as to concentrate their fire to best effect. Detachments (normally of at least 2 guns) as direct support to infantry or cavalry could still be made but these were the exception rather than the rule. In some nations pairs of small calibre guns were still permanently attached to infantry as “battalion guns” but this practice died out during the Napoleonic Wars.
A further development in artillery mobility was the extension of the 18th century concept of “galloper guns” into true horse artillery where all gunners were mounted or rode on limbers. These were used not just to support cavalry but in order to provide a highly mobile artillery support to any attack, as well as providing artillery reserves capable of rapid response in defence.
There were various changes in artillery battery composition throughout the Napoleonic wars. A slightly simplistic “snapshot” of typical battery sizes is shown in Table 2 :
There are many detailed variations hidden within such an analysis. The number of ammunition caissons or other support vehicles per battery varied between nations and also between different types of battery within nations. This affected total battery size. Several nations had the practice of supplementing their professional gun crews with untrained infantrymen (or semi-trained artillery labourers in the case of the Austrians). The British did not and so had a larger proportion of trained artillerymen per gun. There were differences in practice as to whether artillerymen or train personnel crewed certain support vehicles and in some nations train personnel were incorporated into the artillery companies.
On occasions several batteries could be formed together into a single fire unit. The French and Russians were particularly keen on such “Grand Batteries” but the fire control problems were immense. Only nations with high ratios of artillery to other arms could form such Grand Batteries easily. Some nations again had well defined organisations of light and medium artillery providing direct support to cavalry and infantry whilst heavy artillery was kept in reserve and could well be used as a nucleus for Grand Batteries.
The technical advances in artillery played a most significant part in the development of Napoleonic tactics. The flexibility and fluidity of such warfare, compared to those more structured tactics of the 18th century, was to a great part enabled by the greater mobility of artillery. Without this, combined arms tactics would not have been able to develop in the way in which they did. The ability of the artillery to accompany troops in an assault, or to reposition themselves rapidly on the battlefield in response to a new situation, was crucial to successful tactics of the period.
 The Art of Warfare in the Age of Marlborough. David Chandler. P141
 Mirabeau and Mauvillon, quoted in The Army of Frederick the Great. Christopher Duffy. P169
 An Ensign in the Peninsular War. The Letters of John Aitchison. P10
 Recollections of Colonel de Gonneville. Part 2. P6
 King Georges Army 1740-1793 (3). Stuart Reid and Paul Chappell. P20
 The Bombardier and Pocket Gunner. Adye. P75